'Shigeru', whose body is weakened and needs nursing care, lives with his son and wife, 'Tamaki' and 'Toshifumi'. Shigeru tends to get depressed about her crippled body, but one day she witnesses her son and his wife have sex, and there she notices that her own penis is erect. Shigeru disguises himself as a frail old man and commits erotic acts, while Tamaki refuses to refuse.
